Try a constant pressure massage instead of the thumping. Pressure should be high enough that the sensation is intense but not painful. The goal is to get muscles around the base of your skull to relax. I was amazed at how quickly it had an effect

Just tried this and it did temporarily stop the tone for a moment. Easy to do, instant relief. Simple massage to the muscles near the base of the skull.

A physical therapist commented that tight muscles contribute. Hopefully practicing this regularly will prolong the effects.